 /*******************************************************************************
  * Copyright (c) 2003, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.ui.navigator;

 import java.util.Set ;

 import org.eclipse.jface.viewers.IStructuredSelection;
 import org.eclipse.ui.internal.navigator.extensions.OverridePolicy;

 /**
  *
  * The descriptor provides a handle to a content extension. Information such as
  * the Id, the name, the priority, and whether the descriptor provides one or
  * more root elements is provided.
  *
  *
  * <p>
  * There is one {@link INavigatorContentExtension} for each content service.
  * There is only one {@link INavigatorContentDescriptor} for each extension.
  * </p>
  *
  * <p>
  * This interface is not intended to be implemented by clients.
  * </p>
  *
  * @since 3.2
  *
  */
 public interface INavigatorContentDescriptor {

     /**
      * Returns the navgiator content extension id
      *
      * @return the navgiator content extension id
      */
     String getId();

     /**
      * Returns the name of this navigator extension
      *
      * @return the name of this navigator extension
      */
     String getName();

     /**
      * Returns the priority of the navigator content extension.
      *
      * @return the priority of the navigator content extension. Returns 0 (zero)
      * if no priority was specified.
      */
     int getPriority();

     /**
      * The enabledByDefault attribute specifies whether an extension should be
      * activated in the context of a viewer automatically. Users may override
      * this setting through the "Types of Content" dialog.
      *
      * @return true if the extension is enabled by default.
      */
     boolean isActiveByDefault();

     /**
      * Determine if this content extension is enabled for the given element.
      *
      * @param anElement
      * The element that should be used for the evaluation.
      * @return True if and only if the extension is enabled for the element.
      */
     boolean isTriggerPoint(Object anElement);

     /**
      * Determine if this content extension could provide the given element as a
      * child.
      *
      * <p>
      * This method is used to determine what the parent of an element could be
      * for Link with Editor support.
      * </p>
      *
      * @param anElement
      * The element that should be used for the evaluation.
      * @return True if and only if the extension might provide an object of this
      * type as a child.
      */
     boolean isPossibleChild(Object anElement);

     /**
      * A convenience method to check all elements in a selection.
      *
      * @param aSelection
      * A non-null selection
      * @return True if and only if every element in the selection is a possible
      * child.
      */
     boolean arePossibleChildren(IStructuredSelection aSelection);

     /**
      * @return Returns the suppressedExtensionId or null if none specified.
      */
     String getSuppressedExtensionId();

     /**
      * @return Returns the overridePolicy or null if this extension does not
      * override another extension.
      */
     OverridePolicy getOverridePolicy();

     /**
      * @return The descriptor of the <code>suppressedExtensionId</code> if
      * non-null.
      */
     INavigatorContentDescriptor getOverriddenDescriptor();

     /**
      *
      * Does not force the creation of the set of overriding extensions.
      *
      * @return True if this extension has overridding extensions.
      */
     boolean hasOverridingExtensions();

     /**
      * @return The set of overridding extensions (of type
      * {@link INavigatorContentDescriptor}
      */
     Set getOverriddingExtensions();

     /**
      * @return true if the extension's content provider may adapt to a {@link SaveablesProvider}.
      */
     boolean hasSaveablesProvider();

 }

